Refrigerant condition detection device, refrigerant condition detection method, and temperature control system

ABSTRACT

A refrigerant condition detection device ( 40 A) according to an embodiment includes: a temperature information acquisition unit ( 41 ) that acquires a temperature of a refrigerant flowing out from the condenser of a refrigeration circuit having a compressor, the condenser, an expansion valve, and an evaporator, and also acquires a temperature of a cooling fluid before it cools the refrigerant in the condenser; and a refrigerant condition determination unit ( 42 ) that determines that a leakage or shortage of the refrigerant occurs, when a difference between the temperature of the refrigerant and the temperature of the cooing fluid, which are acquired by the temperature information acquisition unit ( 41 ), exceeds a threshold value previously recorded.

TECHNICAL FIELD

The present invention relates to a refrigerant condition detectiondevice, a refrigerant condition detection method, and a temperaturecontrol system.

BACKGROUND ART

When a refrigeration circuit leaks a refrigerant to run short of therefrigerant, a refrigeration capacity may lower and/or another problemmay occur, for example. Thus, some measures should be taken as soon aspossible.

Various technologies for detecting a refrigerant leakage have beenproposed in the past. For example, JP2016-121867A discloses a techniquefor detecting a refrigerant leakage by detecting a compressor intakepressure, an evaporator pressure, a compressor discharge pressure, acondenser pressure, a compressor intake temperature, an evaporatoroutlet temperature, a compressor discharge temperature, a condenserinlet temperature and so on, and using these detected values asparameters. In addition, WO2017/175300 discloses a technique ofproviding an indoor unit of an air conditioner with a refrigerantdetection device that detects a refrigerant having leaked outside.

DISCLOSURE OF THE INVENTION

However, the technique of JP2016-121867A requires many sensors fordetecting pressures, temperature, etc., and a lot of parameters are usedto determine a refrigerant leakage. In addition, the technique ofWO2017/175300 directly detects a refrigerant that has leaked outside bythe refrigerant detection device. Thus, it is difficult to detect theleaked refrigerant at a distance from the refrigerant detection device,and it is difficult to accurately detect a refrigerant shortage.

In consideration of the aforementioned known technique, the presentinventor conducted intensive research to detect a refrigerant leakage ora refrigerant shortage very simply and accurately. The present inventorthen found that, when a refrigerant shortage occurs, an outlettemperature of a condenser becomes higher than the outlet temperature ofthe condenser which does not run short of the refrigerant. The presentinventor also found that this phenomenon is caused by the fact thatunder the refrigerant shortage, an amount of the refrigerant condensedin the condenser is less than a planned or expected amount ofcondensation, so that a high-temperature refrigerant still in a gaseousstate tends to flow out from a condenser outlet into a downstream pipe.

The present invention has been made in view of the above findings. Theobject of the present invention is to provide a refrigerant conditiondetection device, a refrigerant condition detection method, and atemperature control system, which are capable of simply and accuratelydetecting a leakage or shortage of a refrigerant in a refrigerantcircuit.

A refrigerant condition detection device according toe the presentinvention comprises:

a temperature information acquisition unit that acquires a temperatureof a refrigerant flowing out from a condenser of a refrigeration circuithaving a compressor, the condenser, an expansion valve, and anevaporator, and also acquires a temperature of a cooling fluid before itcools the refrigerant in the condenser; and

a refrigerant condition determination unit that determines that aleakage or shortage of the refrigerant occurs, when a difference betweenthe temperature of the refrigerant and the temperature of the cooingfluid, which are acquired by the temperature information acquisitionunit, exceeds a threshold value previously recorded.

The condenser may be a liquid-cooled heat exchanger, and the cooingfluid may be a liquid.

The condenser may have a first condensing part and a second condensingpart that condenses the refrigerant flowing out from the firstcondensing part; and

the temperature information acquisition unit may acquire a temperatureof the refrigerant flowing out from the second condensing part, and atemperature of the cooling fluid before it cools the refrigerant in thesecond condensing part.

A refrigerant condition detection method according to the presentinvention comprises:

a temperature information acquisition step that acquires a temperatureof a refrigerant flowing out from a condenser of a refrigeration circuithaving a compressor, the condenser, an expansion valve, and anevaporator, and also acquires a temperature of a cooling fluid before itcools the refrigerant in the condenser; and

a refrigerant condition determination step that determines that aleakage or shortage of the refrigerant occurs when a difference betweenthe temperature of the refrigerant and the temperature of the coolingfluid, which are acquired in the temperature information acquisitionstep, exceeds a threshold value previously recorded.

The refrigerant condition detection method according to the presentinvention may further comprise a filling step that fills therefrigeration circuit with a predetermined amount of the refrigerantthat enables an operation of the refrigeration circuit by which adifference between an acquired temperature of the refrigerant flowingout from the condenser and an acquired temperature of the cooling fluidbefore it cools the refrigerant in the condenser becomes the thresholdvalue or below,

wherein a leakage or shortage of the refrigerant may be determined bythe temperature information acquisition step and the refrigerantcondition determination step that are performed after the filling step.

During the operation of the refrigeration circuit after the fillingstep, the refrigeration circuit may cool the refrigerant in thecondenser such that the refrigerant condensed by the condenser covers anoutlet of the condenser.

A temperature control system according to the present inventioncomprises:

a refrigeration circuit having a compressor, a condenser, an expansionvalve, and an evaporator; and

the aforementioned refrigeration condition detection device.

When the refrigeration circuit is filled with a predetermined amount ofthe refrigerant, the refrigeration circuit may be capable of performingan operation by which a difference between a temperature of therefrigerant and a temperature of the cooling fluid, which are acquiredby the refrigerant condition detection device, becomes the thresholdvalue or below.

When the refrigeration circuit is filled with the predetermined amountof the refrigerant, the refrigeration circuit may be capable of coolingthe refrigerant in the condenser such that the refrigerant condensed bythe condenser covers the outlet of the condenser.

The temperature control system according to the present invention mayfurther comprise a fluid flow device that causes a fluid whosetemperature is controlled by the evaporator to flow.

The present invention can simply and accurately a leakage or shortage ofa refrigerant in a refrigeration circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a schematic structure of a temperature controlsystem according to a first embodiment of the present invention.

FIG. 2A is a schematic sectional view of a condenser provided on arefrigeration circuit of the temperature control system shown in FIG. 1.

FIG. 2B is a schematic sectional view of the condenser provided on therefrigeration circuit of the temperature control system shown in FIG. 1.

FIG. 3 is a view showing a schematic structure of the temperaturecontrol system according to a second embodiment of the presentinvention.

FIG. 4 is a view showing a schematic structure of the temperaturecontrol system according to a third embodiment of the present invention.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Respective embodiments of the present invention are described herebelow.

First Embodiment

FIG. 1 is a view showing a schematic structure of a temperature controlsystem 1 according to a first embodiment of the present invention. Thetemperature control system 1 according to this embodiment comprises arefrigeration circuit 10, a first cooling fluid flow device 21, a secondcooing fluid flow device 22, a temperature control target fluid flowdevice 30, and a controller 40.

The refrigeration circuit 10 has a compressor 11, a condenser 12, areceiver tank 13, an expansion valve 14, and an evaporator 15. Thecompressor 11, the condenser 12, the receiver tank 13, the expansionvalve 14, and the evaporator 15 are connected by pipe members such thata refrigerant is circulated in this order.

The compressor 11 compresses a low-temperature and low-pressure gaseousrefrigerant flowing out from the evaporator into the high-temperatureand high-pressure gaseous refrigerant, and supplies it to the condenser12. The condenser 12 cools, by means of a cooling fluid, the refrigerantcompressed by the compressor 11 to condense it to the high-pressureliquid refrigerant having a predetermined cooling temperature.

In this embodiment, the condenser 12 has a first condensing part 121,and a second condensing part 122 that condenses the refrigerant flowingout from the first condensing part 121. The refrigerant passing throughthe first condensing part 121 is cooled by a first cooling fluid whichis supplied by the first cooing fluid flow device 21 to the firstcondensing part 121. The refrigerant passing through the secondcondensing part 122 is cooled by a second cooling fluid which issupplied by the second fluid flow device 22 to the second condensingpart 122.

Each of the first condensing part 121 and the second condensing part 122is formed by a liquid-cooled heat exchanger, specifically, a plate-typeheat exchanger. However, the first condensing part 121 and the secondcondensing part 122 may be air-cooled heat exchangers.

The receiver tank 13 receives the refrigerant, which has been condensedby the condenser 12 to the liquid refrigerant, and stores it therein.The refrigerant stored in the receiver tank 13 flows toward theexpansion valve 14. The expansion valve 14 expands to decompress therefrigerant supplied from the receiver tank 13 into the low-temperatureand low-pressure refrigerant in a liquid state or gas-liquid mixedstate, and supplies it to the evaporator 15. In this embodiment, theevaporator 15 heat-exchanges between the refrigerant, which has beensupplied thereto, and a temperature control target fluid, which iscaused to flow by the temperature control target fluid flow device 30.The refrigerant having been heat-exchanged with the temperature controltarget fluid becomes again the low-temperature and low-pressure gaseousrefrigerant. The refrigerant flows out from the evaporator 15 and isagain compressed by the compressor 11.

The first cooling fluid flow device 21 supplies the first condensingpart 121 with the first cooing fluid, and the second cooling fluid flowdevice 22 supplies the second condensing part 122 with the secondcooling fluid. As described above, since the first condensing part 121and the second condensing part 122 are formed by liquid-cooled heatexchangers in this embodiment, liquids are used as the first coolingfluid and the second cooling fluid.

The first cooling fluid and the second cooling fluid, which are liquids,may be water or another fluid. When the first condensing part 121 andthe second condensing part 122 are formed by air-cooled heat exchangers,the first cooling fluid and the second cooling fluid may be air.

In this embodiment, the second cooling fluid flow device 22 has a pump22A. By controlling a driving force of the pump 22A, a flow rate of thesecond cooling fluid to be supplied to the second condensing part 122can be regulated. Thus, a cooling capacity of the refrigerant in thesecond condensing part 122 can be regulated.

As described above, the temperature control target fluid flow device 30causes the temperature control target fluid, which heat-exchanges withthe refrigerant in the evaporator 15, to flow. The temperature controltarget fluid caused to flow by the temperature control target fluid flowdevice 30 may be either a gas or a liquid.

When the temperature control target fluid is a gas, the temperaturecontrol target fluid flow device 30 may be formed by a fan or the like.On the other hand, when the temperature control target fluid is aliquid, the temperature control target fluid flow device 30 may beformed by a liquid flow path, a pump for causing a liquid to flow, etc.

The refrigeration circuit 10 is provided with a refrigerant temperaturesensor 16 that detects a temperature of the refrigerant flowing out fromthe second condensing part 122, and a refrigerant pressure sensor 17that detects a pressure of the refrigerant flowing out from the secondcondensing part 122. Specifically, the refrigerant temperature sensor 16detects a temperature of the refrigerant that has flown out from thesecond condensing part 122 but does not yet flow into the receiver tank13. In other words, the refrigerant temperature sensor 16 detects atemperature inside a pipe member connected to an outlet of the secondcondensing part 122. The refrigerant pressure sensor 17 detects thepressure of a refrigerant that has flown out from the second condensingpart 122 but does not yet flow into the receiver tank 13. In otherwords, the refrigerant pressure sensor 17 detects a pressure inside thepipe member connected to the outlet of the second condensing part 122.

The second cooling fluid flow device 22 is provided with a cooing fluidtemperature sensor 22B. The cooling fluid flow device 22B detects atemperature of the second cooling fluid temperature before it cools therefrigerant in the second condensing part 122. In other words, thecooling fluid temperature sensor 22B detects a temperature inside a partof a pipe member, the part being upstream of the second condensing part122. The second cooling fluid flow device 22 causes the second coolingfluid to flow through the pipe.

The controller 40 can control operations of the respective units of therefrigeration circuit 10, the pump 22A of the second cooling fluid flowdevice 22 and the like, and can acquire information from theaforementioned respective sensors 16, 17 and 22B. The controller 40 maycomprise, for example, a computer equipped with a CPU, a ROM, a RAM,etc. to control operations of the aforementioned respective units inaccordance with a stored program.

The controller 40 has a temperature information acquisition unit 41, arefrigerant condition determination unit 42, an operation control unit43, and an output unit 44.

The temperature information acquisition unit 41 acquires, from therefrigerant temperature sensor 16, a temperature of the refrigerantflowing out from the second condensing part 122 of the condenser 12, andacquires, from the cooling fluid temperature sensor 22B, a temperatureof the second cooling fluid temperature before it cools the refrigerantin the second condensing part 122.

The refrigerant condition determination unit 42 determines that aleakage or shortage of the refrigerant occurs, when a difference betweenthe temperature of the refrigerant and the temperature of the secondcooling fluid, which are acquired by the temperature informationacquisition unit 41, exceeds a previously recorded threshold value.Herein, the temperature information acquisition unit 41 and therefrigerant condition judgment unit 42 constitute a refrigerantcondition detection device 40A.

The operation control unit 43 controls operations of the respectiveunits of the refrigeration circuit 10, the pump 22A of the secondcooling fluid flow device 22 and the like.

The output unit 44 displays a warning on a display device, not shown,when the refrigerant condition determination unit 42 determines that aleakage or shortage of the refrigerant occurs.

Herebelow, a determination flow of a leakage or shortage of therefrigerant by the refrigerant condition detection device 40A in thisembodiment is described.

A structure of the second condensing part 122, and an inside conditionof the second condensing part 122 during operation of the refrigerationcircuit 10 are described first. FIGS. 2A and 2B are schematic sectionalviews of the second condensing part 122 formed of a plate-type heatexchanger. As shown in FIG. 2A, the condensing part 122 has a pluralityof plate members 122A that are stacked (arranged) such that a flow paththrough which the refrigerant or the second cooling fluid flows isformed between the adjacent plate members 122A. The plate members 122Aform a flow path 122B for refrigerant (refrigerant flow path 122B) and aflow path 122C for second cooling fluid (second-cooling-fluid flow path122C), which are alternately arranged in the stacking direction.

A refrigerant inlet 122D and a refrigerant outlet 122E are connected toa plate member 122A which is positioned on one end of the stackingdirection of the plate members 122A. As shown by a white arrow, therefrigerant flows from the refrigerant inlet 122D to the second coolingfluid flow path 122B, and flows out from the refrigerant outlet 122E.The refrigerant inlet 122D and the refrigerant outlet 122E are disposeddistant from each other in a direction orthogonal to the stackingdirection. In this embodiment, the second condensing part 122 isarranged such that the refrigerant inlet 122D is positioned above therefrigerant outlet 122E in an up and down direction. The refrigerantinlet 122D may be a part of a pipe member connecting the firstcondensing part 121 and the second condensing part 122, or a memberseparated from the pipe member. Similarly, the refrigerant outlet 122Emay be a part of a pipe member connecting the second condensing part 122and the receiver tank 13, or may be a member separated from the pipemember.

On the other hand, although not shown, a second cooling fluid inlet anda second cooling fluid outlet are connected to a plate member 122A whichis positioned on one end of the stacking direction. As shown by ahatched arrow, the second cooling fluid flows from the second coolingfluid inlet to the second cooling fluid flow path 122C, and flows outfrom the second cooling fluid outlet.

The second cooling fluid inlet and the second cooling fluid outlet aredisposed distant from each other in the direction orthogonal to thestacking direction. The second cooling fluid inlet is provided on thesame side as the refrigerant outlet 122E in the direction orthogonal tothe stacking direction, and the second cooling fluid outlet is providedon the same side as the refrigerant inlet 122D in the directionorthogonal to the stacking direction. Thus, in this embodiment, thesecond cooling fluid outlet is positioned above the second cooling fluidinlet in the up and down direction. However, the second cooling fluidinlet may be provided on the same side as the refrigerant inlet 122D inthe direction orthogonal to the stacking direction, and the coolingfluid outlet may be provided on the same side as the refrigerant outlet122E in the direction orthogonal to the stacking direction.

A symbol LM shown in FIG. 2A shows the refrigerant in a liquid statewhich has been condensed by the second cooing fluid and accumulated at abottom of the second condensing part 122. In FIG. 2A, a liquid levelheight of the liquid refrigerant LM exceeds an upper end of therefrigerant outlet 122E, so that the liquid refrigerant LM covers therefrigerant outlet 122E.

In this embodiment, in order that the liquid refrigerant LM covers therefrigerant outlet 122E, the operation control unit 43 of the controller40 controls the pump 22A of the second cooling fluid flow device 22depending on a refrigerant pressure value from the refrigerant pressuresensor 17.

Specifically, when a cooling capacity of the second cooling fluid flowdevice 22 is low so that the refrigerant is not sufficiently condensed,the liquid level height of the refrigerant LM accumulated at the bottomof the second condensing part 122 may not exceed the upper end of therefrigerant outlet 122E and the refrigerant in a gaseous state may enterthe refrigerant outlet 122E. At this time, a pressure value of therefrigerant, which is detected by the refrigerant pressure sensor 17,becomes larger than a case in which the refrigerant outlet 122E isfilled with the liquid refrigerant. Thus, a condition in which theliquid refrigerant LM covers the refrigerant outlet 122E can be formedby firstly determining as a threshold value a pressure value detected bythe refrigerant pressure sensor 17 when the refrigerant outlet 122E isfilled with the liquid refrigerant, and by controlling the pump 22A ofthe second cooling fluid flow device 22 depending on a pressure value ofthe refrigerant from the refrigerant pressure sensor 17.

As described above, when the liquid refrigerant LM covers therefrigerant outlet 122E, a difference between a temperature of therefrigerant, which is detected by the refrigerant temperature sensor 16,and a temperature of the second cooling fluid, which is detected by thecooling fluid temperature sensor 22B before the second cooling fluidcools the refrigerant, is small. Ideally, the temperatures are the same.When a difference between a temperature of the refrigerant detected bythe refrigerant temperature sensor 16 and a temperature of the secondcooling fluid detected by the cooling fluid temperature sensor 22B issmall, it can be said that a normal operation by which the liquidrefrigerant LM covers the refrigerant outlet 122E is performed, and thatthe refrigeration circuit 10 is filled with a proper predeterminedamount of the refrigerant. Such a predetermined amount of therefrigerant can be determined through calculation or verification,taking into consideration the size of the refrigeration circuit 10 andthe refrigeration capacity required therefor.

On the other hand, although the cooling capacity of the second coolingfluid flow device 22 is controlled such that the liquid refrigerant LMcovers the refrigerant outlet 122E, as described above, there is apossibility that the liquid level height of the refrigerant LMaccumulated on the bottom of the second condensing part 122 does notexceed the upper end of the refrigerant outlet 122E, as shown in FIG.2B. Then, it can be assumed that a refrigerant shortage occurs in therefrigerant circuit 10 because of a leakage of the refrigerant or thelike. In this case, the refrigerant in a gaseous state flows into therefrigerant outlet 122E so that a temperature of the refrigerantdetected by the refrigerant temperature sensor 16 becomes higher than acase in which the refrigerant outlet 122E is filled with the liquidrefrigerant. As a result, a difference between a temperature of therefrigerant, which is detected by the refrigerant temperature sensor 16,and a temperature of the second cooling fluid, which is detected by thecooling fluid temperature sensor 22B, becomes large.

The present inventor has found that, when a leakage or shortage of therefrigerant occurs in the refrigerant circuit 10, a difference between atemperature of the refrigerant, which is detected by the refrigeranttemperature sensor 16, and a temperature of the second cooling fluid,which is detected by the cooling fluid temperature sensor 22B, becomeslarge. Thus, the present inventor came to adopt the refrigerantcondition detection device 40A which determines that a leakage orshortage of the refrigerant occurs, when a difference therebetweenexceeds a previously recorded threshold value.

The present inventor has found that a threshold value for determining aleakage or shortage of a refrigerant is preferably 2° C. or higher, morepreferably between 2° C. or higher and 6° C. or lower, and furtherpreferably between 2° C. or higher and 4° C. or lower. A threshold valueset in such a range improves determination accuracy of a leakage orshortage of a refrigerant.

In the determination of a leakage or shortage of the refrigerant, amoving average value of a difference between a temperature of therefrigerant detected by the refrigerant temperature sensor 16 and atemperature of the second cooling fluid detected by the cooling fluidtemperature sensor 22B may be calculated, and this moving average valuemay be compared with the aforementioned threshold value. The movingaverage value may be calculated using a difference between a temperatureof the refrigerant detected by the refrigerant temperature sensor 16 anda temperature of the second cooling fluid detected by the cooling fluidtemperature sensor 22B at three or more detection points in a detectionperiod of three seconds or more. The use of the moving average value canimprove determination accuracy by suppressing influence of noise in thesensors.

As described above, in this embodiment, the refrigerant circuit 10 isprovided with the refrigerant condition detection device 40A. Therefrigerant condition detection device 40A comprises the temperatureinformation acquisition unit 41 that acquires a temperature of therefrigerant flowing out from the second condensing part 122 and acquiresa temperature of the second cooling fluid temperature before it coolsthe refrigerant in the second condensing part 122, and the refrigerantcondition determination unit 42 that determines that a leakage orshortage of a refrigerant occurs when a difference between thetemperature of the refrigerant and the temperature of the second coolingfluid, which are acquired by the temperature information acquisitionunit 41, exceeds a threshold value previously recorded.

Such a refrigerant condition detection device 40A uses the lesser numberof parameters for determination of a leakage or shortage of therefrigerant. In addition, the use of a temperature as a determinationparameter can improve determination accuracy of a leakage or shortage ofthe refrigerant. Namely, in a case where a temperature of therefrigerant in the refrigeration circuit 10 is detected, suddenfluctuation and/or noise detection can be suppressed as compared with acase in which a pressure is detected.

Thus, this embodiment enables simple and accurate detection of a leakageor shortage of a refrigerant in the refrigeration circuit 10.

Second Embodiment

Next, a temperature control system 2 according to a second embodiment isdescribed with reference to FIG. 3. In the following description, onlydifferences from the first embodiment are described.

As shown in FIG. 3, in this embodiment, a condenser 12 is formed by asingle liquid-cooled heat exchanger. The condenser 12 is supplied with acooling fluid caused to flow by a cooling fluid flow device 20. Thecooling fluid flow device 20 has a pump 22A that regulates a flow rateof the cooling fluid, and a cooling fluid temperature sensor 22B. Thecooling fluid temperature sensor 22B detects a temperature of thecooling fluid before it cools the refrigerant in the condenser 12.

In a refrigerant condition detection device 40A, a temperatureinformation acquisition unit 41 acquires, from a refrigerant temperaturesensor 16, a temperature of the refrigerant flowing out from thecondenser 12, and acquires, from the cooing fluid temperature sensor22B, a temperature of the cooling fluid before it cools the refrigerantin the condenser 12. A refrigerant condition determination unit 42determines that a leakage or shortage of the refrigerant occurs, when adifference between the refrigerant temperature and the cooling fluidtemperature, which are acquired by the temperature informationacquisition unit 41, exceeds a previously recorded threshold value.

This embodiment also enables very simple and accurate detection of aleakage or shortage of a refrigerant.

Third Embodiment

Next, a temperature control system 3 according to a third embodiment isdescribed with reference to FIG. 4. In the following description, onlydifferences from the first and second embodiments are described.

In this embodiment, a condenser 12 is formed by a single air-cooled heatexchanger. The condenser 12 is supplied with a cooling fluid which is agas caused to flow by an air-cooling device 24 driving its fan. Thecooling fluid may be air. A cooling fluid temperature sensor 22Bprovided on the air-cooling device 24 detects a temperature of thecooling fluid supplied to the condenser 12.

In a refrigerant condition detection device 40A, a temperatureinformation acquisition unit 41 acquires, from a refrigerant temperaturesensor 16, a temperature of the refrigerant flowing out from thecondenser 12, and acquires, from the cooling fluid temperature sensor22B, a temperature of the gaseous cooling fluid before it cools therefrigerant in the condenser 12. A refrigerant condition determinationunit 42 determines that a leakage or shortage of the refrigerant occurs,when a difference between the refrigerant temperature and the coolingfluid temperature, which are acquired by the temperature informationacquisition unit 41, exceeds a previously recorded threshold value.

This embodiment also enables very simple and accurate detection of aleakage or shortage of a refrigerant.

Although the embodiments of the present invention have been describedabove, the present invention is not limited to the aforementionedembodiments and an be variously modified. For example, in theaforementioned respective embodiments, the refrigeration circuit 10 isprovided with the receiver tank 13, but the refrigeration circuit 10need not have the receiver tank 13.

1. A refrigerant condition detection device comprising: a temperatureinformation acquisition unit that acquires a temperature of arefrigerant flowing out from a condenser of a refrigeration circuithaving a compressor, the condenser, an expansion valve, and anevaporator, and also acquires a temperature of a cooling fluid before itcools the refrigerant in the condenser; and a refrigerant conditiondetermination unit that determines that a leakage or shortage of therefrigerant occurs, when a difference between the temperature of therefrigerant and the temperature of the cooing fluid, which are acquiredby the temperature information acquisition unit, exceeds a thresholdvalue previously recorded.
 2. The refrigerant condition detection deviceaccording to claim 1, wherein the condenser is a liquid-cooled heatexchanger, and the cooing fluid is a liquid.
 3. The refrigerantcondition detection device according to claim 1, wherein: the condenserhas a first condensing part and a second condensing part that condensesthe refrigerant flowing out from the first condensing part; and thetemperature information acquisition unit acquires a temperature of therefrigerant flowing out from the second condensing part, and atemperature of the cooling fluid before it cools the refrigerant in thesecond condensing part.
 4. A refrigerant condition detection methodcomprising: a temperature information acquisition step that acquires atemperature of a refrigerant flowing out from the condenser of arefrigeration circuit having a compressor, the condenser, an expansionvalve, and an evaporator, and also acquires a temperature of a coolingfluid before it cools the refrigerant in the condenser; and arefrigerant condition determination step that determines that a leakageor shortage of the refrigerant occurs when a difference between thetemperature of the refrigerant and the temperature of the cooling fluid,which are acquired in the temperature information acquisition step,exceeds a threshold value previously recorded.
 5. The refrigerantcondition detection method according to claim 4, further comprising afilling step that fills the refrigeration circuit with a predeterminedamount of the refrigerant that enables an operation of the refrigerationcircuit by which a difference between an acquired temperature of therefrigerant flowing out from the condenser and an acquired temperatureof the cooling fluid before it cools the refrigerant in the condenserbecomes the threshold value or below, wherein a leakage or shortage ofthe refrigerant is determined by the temperature information acquisitionstep and the refrigerant condition determination step that are performedafter the filling step.
 6. The refrigerant condition detection methodaccording to claim 5, wherein during the operation of the refrigerationcircuit after the filling step, the refrigeration circuit cools therefrigerant in the condenser such that the refrigerant condensed by thecondenser covers an outlet of the condenser.
 7. A temperature controlsystem comprising: a refrigeration circuit having a compressor, acondenser, an expansion valve, and an evaporator; and the refrigerantcondition detection device according to claim
 1. 8. The temperaturecontrol system according to claim 7, wherein, when the refrigerationcircuit is filled with a predetermined amount of the refrigerant, therefrigeration circuit is capable of performing an operation by which adifference between a temperature of the refrigerant and a temperature ofthe cooling fluid, which are acquired by the refrigerant conditiondetection device, becomes the threshold value or below.
 9. Thetemperature control system according to claim 8, wherein, when therefrigeration circuit is filled with the predetermined amount of therefrigerant, the refrigeration circuit is capable of cooling therefrigerant in the condenser such that the refrigerant condensed by thecondenser covers the outlet of the condenser.
 10. The temperaturecontrol system according to claim 7, further comprising a fluid flowdevice that causes a fluid whose temperature is controlled by theevaporator to flow.
 11. The refrigerant condition detection deviceaccording to claim 2, wherein: the condenser has a first condensing partand a second condensing part that condenses the refrigerant flowing outfrom the first condensing part; and the temperature informationacquisition unit acquires a temperature of the refrigerant flowing outfrom the second condensing part, and a temperature of the cooling fluidbefore it cools the refrigerant in the second condensing part.
 12. Atemperature control system comprising: a refrigeration circuit having acompressor, a condenser, an expansion valve, and an evaporator; and therefrigerant condition detection device according to claim
 2. 13. Atemperature control system comprising: a refrigeration circuit having acompressor, a condenser, an expansion valve, and an evaporator; and therefrigerant condition detection device according to claim
 3. 14. Thetemperature control system according to claim 8, further comprising afluid flow device that causes a fluid whose temperature is controlled bythe evaporator to flow.
 15. The temperature control system according toclaim 9, further comprising a fluid flow device that causes a fluidwhose temperature is controlled by the evaporator to flow.